Switch and signal control system for railroads



Oct. 21, 1952 w. L. LIVINGSTON 2,615,124

SWITCH AND SIGNAL CONTROL. SYSTEM FOR RAILROADS Filed 001;. 14, 1946 IN VEN TOR.

IG. 2. 14; Y

64- l BY mums WZ QC? M W,

Patented Get. 21, 1952 SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS "Waltrus L. Livingston, Rochester, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application October 14, 1946, Serial No. 703,173

3 Claims.

This invention relates to switch and signal control system for railways, and it more particularly relates to improvements in checking that a switch is in correspondence with the switch position last designated before a signal can be cleared.

It is well known in railway signaling practice that the use of polar control circuits for the control of switch position repeater relays is desirable from the standpoint of reducing to a minimum the possibility of false energization of such relays due to their control wires becoming crossed with wires providing an extraneous source of energy. Such extraneous energy cannot be effective when a track switch is in mid-stroke, because the switch repeater relay control circuit is shunted at that time by the point detector contact mechanism operated by the switch points, the shunt being removed only when that track switch is moved to its full normal or reverse position. When the track switch is in its'fully operated normal or reverse position, the application of energy from an extraneous source, in order to provide false relay operation, must be applied across both control wires of the switch position repeater relay, must be of the opposite polarity to the polarity normally applied for that position of the track switch, and must be of a potential substantially twice the normal potential in order to provide suflicient energy to operate the switch repeater relay in opposition to its normal polarity of energization. A polar neutral relay thus controlled is used to control neutral correspondence relays for indicating correspondence between the track switch and the position of the track switch which has been last manuallydesignated by an operator.

An object of the present invention is to extend the polar cross protection feature of the switch repeater relay circuit to include the circuits of the correspondence relays, such correspondence relays being preferably of a biased polar type having a structure to cause such relays to be picked up against a spring and/or gravity biasing action applied to the relay armatures only when the relay windings are energized with a particular polarity.

Another object of the present invention is to provide a dependable polarized circuit organization for the control of correspondence relays whereby the usual polar neutral switch position repeater relays are not required.

Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawing, and in part pointed out as the description progresses.

In describing the invention in detail, reference is made to the accompanying drawing in which the symbols and are used to indicate connections to respectivepositive and negative terminals of a suitable direct current source of energy, and in which: h

Fig. l is one embodiment of thepresent invention as applied to a simple track layout; and,

Fig. 2 illustrates a modification in .the control of switch correspondence relays.

For the purpose of simplification of the disclosure of the present invention, a simple embodiment is chosen in which a main track ill (see Fig. l) is connected to a passing siding H by a power operated switch-W, the signals 2A and 213 being provided for governing eastbound traffic (to the right) through the switch W in its respective normal and reverse positions, and the signals 3A and 313 being provided for governing westbound trafic (to the left) through'the track switch W in its respective normal and reverse positions. It is believed that it will be readily apparent as the description progresses'that the present invention is in no way limited to the simple track layout of this embodiment, but is readily adaptable to the control of correspondence relays in more complex track layouts most generally encountered in practice.

The trackswitch W can be power operated, by any suitable type of power switch machine such, for example, as by the switch machine disclosed in the patent to W. K. Howe, No.-1,466,90 3, dated September 4, 1923. Such switch machine is assumed to include, or have separately associated therewith, a suitable switch point detector contact mechanism of the general character disclosed, for example, in the patent to C. S. Bushnell, No. 1,517,236, dated November25,-1924. For the purpose of simplification of the present disclosure the contacts of such a mechanism are shown schematically as having movable contact bars [2 and It effective to close circuitsonly in the full normal and full reverse positions of the track switch W, and a contact bar [4 effective to close a circuit only when the track switch W is in mid-stroke.

Although the signals employed in this embodiment of the present inventionare of the searchlight type such, for example, as the type shown in the patent to O. S. Field, Patent No. 2,239,316, dated April 22, 1941, it is to be understood that other suitable types of signals such as semaphore signals, position light signals, or light signals having individual color light units could as well be employed in accordance with the requirements of practice.

It is assumed that the control of the switch and signals of this embodiment of the present invention is accomplished at a control oifice which is preferably located near the track layout. A suitable control machine is located at the control ofiice having a miniature diagram of the track layout with suitable indicator lamps disposed thereon and controlled to provide information to the operator relative to the occupancy of the re spective track sections and the conditions of the switch and signals in accordance with the re quirements of practice.

Control levers are provided on the control machine for the designation of the respective positions to which the track switch W is to be operated, and for the designation of the direction for which a signal is to be cleared. More specifically, a two-position switch control lever SML is provided for designating the respective normal and reverse positions of the track switch W, and a three-position lever SGL is provided for designating signals to be cleared or put to stop. The lever SGL when at its center position designates the signals to be at stop, when in its right-hand position designates the clearing of a signal for governing eastbound traffic, and when at its left-hand position designating the clearing of a signal for governing westbound traific.

Although the control ofilce is assumed to be located relatively close to the track layout and most of the relays can be conveniently located in the control ofiice, it is to be understood that the present invention is equally applicable to a centralized trafiic control system where the control oifice is remotely located from the track layout, and in such case the circuits are so organized and the control apparatus so allocated as between ofiice and held to require a minimum number of line wires extending from the control oflice to the track layout.

The neutral relays NWZ and RWZ are used for applying energy to the operating circuit of the switch machine SM in accordance with the positioning of the switch control lever SML.

The lock stick relay LS is provided according to the usual practice for the purpose of allowing the power operation of the track switch W only when it is safe that such track switch should be operated, such relay being required to be pickedup in order that a change can be effected in the condition of energization of the relays NWZ and RWZ.

The relays NWC and RWC are respective normal and reverse switch corespondence relays used for repeating the positions of the track switch W in correspondence with the switch control relays NWZ and RWZ. For cross protection purposes the relays NW C and RWC are energized by polarized circuits, one relay being responsive to one polarity of energization of a pair of common control wires extending from the switch machine SM, and the other relay being responsive to the opposite polarity of energization of such wires. In order that the relays NWC and RWC can be made responsive to only one polarity, it is desirable that their structure be of a character disclosed, for example, in the application of G. E. Duify, Sr., Ser. No. 542,203, filed June 26, 1944, which has resulted in Patent No. 2,414,583, dated January 25, 1947. A relay of this character is picked up by energization with one polarity at normal voltage, and can be picked up by energization with the opposite polarity only if the voltage is increased to approximately eight times its normal voltage, thus reducing to a minimum the possibility of failure of such a relay to discriminate between the polarities of its energization.

In response to the actuation of the signal control lever SGL to its left-hand or right-hand position, the signal control relays LGZ and RGZ are respectively energized, and the picking up of either of such relays allows the clearing of a signal for the designated direction of traflic as limited by the control circuits for the relay LS to provide that the track switch W must be locked in a position corresponding to the position of the lever SML before a signal can be cleared.

The track relay TB is normally energized by its track circuit through the OS track section T in the manner commonly employed in practice.

For a more detailed consideration of the circuit organization provided to accomplish the above described general mode of operation various typical operating conditions to be encountered in practice will be considered.

The conditions of the system which have been illustrated assume that the track switch W has last been operated to its normal position, and the signal control lever SGL is in its center position, corresponding to the stop indicating positions of the signal mechanisms.

Under such assumed conditions, the relay LS is maintained picked up by energization of its stick circuit which extends from including back contact [5 of relay RGZ, front contact l6 of the approach stick relay RAS, front contact 11 of relay LAS, front contact l8 of relay TR, back contact IQ of relay LGZ, front contact 20 of relay LS, and winding of relay LS to The contacts I3 and I! of relays RAS and LAS respectively which are included in this circuit are contacts of signal approach or time looking relays for signals governing respectively traflic to the right and traflic to the left, such relays, which do not have their control circuits shown, such relays being controlled according to the usual practice for providing approach and time looking as is shown, for example, in Fig. 3 of the patent to T. J. Judge No. 2,350,620, dated June 6, 1944.

The relay NWZ is picked up under the above assumed conditions, with the switch control lever SML in its left-hand position, by the energization of a circuit extending from including contact 2| of lever SML in its left-hand position, front contact 22 of relay LS and winding of relay NWZ, to

Inasmuch as it is assumed that the track switch W has been operated to its normal position in correspondence with the position of the switch control lever SML, the correspondence relay NWC is energized with a polarity to cause such relay to be picked up by a circuit extending from including contact 12 of the point detector contact mechanism of the switch machine SM in its normal positio wire 23, front contact 2d of relay NWZ, winding of relay NWC, back contact 25 of relay RWZ, wire 26 and contact i3 of the point detector contact mechanism of the switch machine SM in its normal position, to It will be noted that the control circuit at both sides of the winding of the relay RWC is open at this time to prevent energization of that relay at contacts 24 and 25 of relays, NWZ and RWZ respectively, although the relay RWC would fail to pick up if it were connected directly in multiple, or in series, with the relay NWC except that its windings were connected with apolarity to render that relay responsive only to the opposite polarity of energization of the wires 23 and 28. Thus it is provided that even if the wires 21 and 28 in the circuit for the relay RWC were to become connected directly to the wires 29 and 30 respectively,

the relay RWC would fail to pick up upon the application of energy to the wires 23 and 26 of a polarity to cause the picking up of relay NWC.

In accordance with relay NWC being in its picked up position and the relay RWC being in its dropped away position, a circuit isconditioned by which the rela ZAG can be-p-icked up for the clearing of signal 2A, if the signal control lever SGL is operated to its right-hand position. Assuming such operation of the lever SGL, a circuit is closed at contact 3! of that lever to energize relay RGZ asindicated by the dotted line 32, such circuit including contact selections as required in practice for the control of either stick or non-stick signals.

Upon the picking up of the relay RGZ, the circuit which has been described by which the relay LS has been maintained energized is opened at back contact l5 to cause the dropping away of that relay, and thus eifect the opening of the pick up circuits for relays NWZ and RW Z at front contacts 22 and 43 respectively to prevent a change in the control circuit for the switch machine SM. The relay NWZ is sufficiently slow in dropping away to be maintained picked up during the shifting of contact 22 of relay LS, and it is thus maintained picked up after the relay LS is dropped away by the enerization of a stick circuit extending from including back contact 44 of relay RWZ, front contact 45 of relay NWZ, back contact 22 of relay LS and winding of relay NWZ, to The dropping away of the relay LS also applies a shunt to the switch machine control wires 46 and 41 by the closing of back contact 48.

The picking up of relay RGZ, under such conditions, causes the picking up of relay ZAG, after relay LS has dropped away, by the energization of a circuit extending from including front contact 33 of relay RGZ, front contact 34 of relay NWC, back contact 35 of relay RWC, front contact 36 of relay TR, back contact '31 of relay LS, back contact 38 of relay LGZ and winding of relay 2AG, to ZAG, by the closing of front contacts 39 and 40, provides for the energization of the mechanism of signal 2A with a polarity as selected by the contacts 4| and 42 of the signal clear repeater relay 4YGP associated with the next signal in advance of signal 2A (not shown) for governing the same direction of traflic.

To consider another typical condition of operation of the system, it will be assumed that the signal control lever SGL is restored to its center position, and that the approach locking relay RAS becomes picked up to close a pick-up circuit for the relay LS. Such circuit extends from including back contact 85 of relay RGZ, front contact it of relay RAS, front contact ll of relay LAS, front contact if! of relay TR, back contact IQ of relay LGZ, contact 55 of lever SML in its left-hand position, front contact 5| of relay NWZ and winding of relay LS, to The checking of correspondence between the lever SML and the relay N NZ in the pick-up circuit of the relay LS, checks that the lever SML is in correspondence with the last position to which the switch W has been operated before a change in the position of such track switch can be ef- The picking up of relay 6 fected, and thus effectively prevents the preconditioning of the position of the track switch W by the actuation of the lever SML out of correspondence with the position of such track switch at a time when the switch is locked by the relay LS being dropped away.

Assuming as another typical operating condition that the operator desires to establish a route over the track switch W in its reverse position, such route being governed by the signal 2B for eastbound trafiic, he first actuates the switch control lever SML to its right-hand position, and then actuates the signal control lever SGL to its right-hand position, The shifting of contact 50 of lever SML does not drop the relay LS because such contact is shunted by the stick contact 20. The series connection of the back contacts 60 and GI of relays NWZ and R WZ respectively in multiple with the stick contact 20 provides that the relay LS can be picked up in case the relays NWZ and RWZ become deenergized at the same time as, for example, by a momentary power interruption. 7

Upon the actuation of the lever SML to its right-hand position, the dropping away of the relay NWZ is effected by the opening of its pick up circuit at contact 2|, the stick circuit for such relay having been opened at contact 22 by the picking up of the relay LS. The relay RWZ is picked up upon the closing of contact 2| of lever SML in its right-hand position by the energization of anobvious circuit including front contact 43 of relay LS.

Relay NWC is dropped away, upon the dropping away of the relay NWZ and the picking up of the relay RWZ, by the opening of its circuit at contacts '24 and 25 respectively, and the relay RWC is connected by the shifting of such contacts to the control wires 23 and 26 extending to'the switch machine SM. Therefore the relay RWC becomes energized momentarily before the switch machine SM has started to operate the track switch W to its reverse position with a polarity applied to the wires 23 and 26 corresponding to'that to which only relay NWC is responsive. Such circuit extends from including contact IQ of the point detector contact mechanism of switch machine SM in its normal position, wire 23, back contact 24 0f relay NWZ, winding of relay RWC, front contact 25 of relay RWZ, wire 26 and contact! of the switch machine SM in its normal posiiton, to The relay RWC cannot bepicked up due to the energization of this circuit because of the polarity of energization being opposite to the polarity required for the picking up of that relay.

With thefront contacts 48 and 49 of the relay LS closed, the closure of front contacts 52 and. 53 of relay RWZ is efiective to energize the switch machine control wires 46 and 41 with a polarityto operate the track switch W to its reverse position. The moment the track switch W starts its operation, the contacts ['2 and I3 of the point detector mechanism shift to their center positions to open their circuit connections, and the contact 14 is effective to shunt the control wires 23 and 25 associated with the controlof the correspondence relays NWC and RWC to thereby guard against the possible energization of either of such relays when the track switch is in mid-stroke as by energization of the control wires 23 and 25 by an extraneous source of energy. 7

When the track switch W completes its operation to its reverse position, the contact M of the point detector mechanism of the switch machine SM opens the shunt which has been applied across the wires 23 and 26, and the subsequent shifting of the contacts i2 and I3 of the point detector mechanism to their reverse positions applies a polarity of energization to the wires 23 and 26 opposite to the polarity which has been described as being applied to such wires for the energization of the relay NWC. The relay RWC thus becomes energized with a polarity to cause the picking up of that relay by a circuit extending from (-1-), including contact [3 of the point detector mechanism of the switch machine SM, wire 26, front contact 25 of relay RWZ, winding of relay RWC, back contact 24 of relay NWZ, wire 23 and contact [2 of the point detector mechanism of switch machine SM in its reverse posiiton, to

Upon the actuation of the lever SGL to its right-hand position, the picking up of relay RGZ is effective to cause the dropping away of the relay LS by opening its circuit at back contact l5, and the relay RWZ is maintained picked up by a stick circuit comparable to that which has been described for the relay NWZ as being effective upon the dropping away of the relay LS. Such stick circuit obviously provides for the completion of the operation of the track switch W, even though the signal control lever SGL is operated to drop the relay LS prior to the completion of the operation of the switch machine SM.

Upon the picking up of the relay RWC, with the relay LS dropped away, a circuit is closed for the picking up of the relay ZBG extending from (l), including front contact 54 of relay RGZ, back contact 55 of relay NWC, front contact 56 of relay RWC, back contact 5?] of relay LS and winding of relay EBG, to Upon the closure of contacts 58 and 59 of relay ZBG, energy is applied to the mechanism of signal 23 of a polarity to provide a caution indication to be displayed by such signal.

It is believed from the typical conditions of operation of the system that have been described that the mode of operation of the system will be readily apparent for the clearing of signals for governing westbound traflic through the track layout of this embodiment of the present invention and for the establishment of routes and governing of traiiic through more complex track layouts to be generally encountered in practice.

It is to be further understood that the present invention is readily applicable to the control of normal and reverse switch correspondence relays in practically any switch and signal control system where relays of like character are employed. An example of where the present invention may be applied to a coded centralized traffic control system is in the application of the present invention to the circuits shown in Fig. 4 of the patent to T. J. Judge, No. 2,350,620, dated June 6, 1944. In that patent the polar neutral relay 3W? could be eliminated according to the present invention, and the relays 3 NCR and BRCR. could be provided as biased polar relays corresponding to the relays NWC and RWC of this embodiment of the present invention. The relays 3WN and 3WR of that patent correspond to the relays NWZ and RWZ respectively of this embodiment of the present invention.

In the application of the present invention to systems having a single polar switch control relay rather than respective normal and reverse switch control relays as shown in Fig. 1, it may be desirable to modify the control of the correspondence relays NWC and RWC as shown in Fig. 2. In Fig. 2 the polar relay WZ is controlled by a suitable polarized circuit indicated by the dotted line 62, the polarity of which is selected by a suitable means such as the contact 63 of the manually operable switch control lever SWL. The relay WZ is assumed to be energized from a split battery or other source of direct current having an intermediate terminal designated as (CN). The positive terminal of a center tap battery is designated by the symbol (B+) and the negative terminal by the symbol (3-). The control circuit for the relay WZ must necessarily conform to the particular application of the present invention in practice, and it may be that such relay has its polarity selected by normal and reverse switch control relays as in an entrance-exit type of interlocking system, rather than being controlled directly by a manually operated lever. Such type of control for the relay WZ is shown, for example, in the patent to A. Langdon, Patent No. 2,148,865, dated February 28, 1939.

When the relays N WC and RWC are controlled as illustrated in Fig. 2, the wire 64 becomes a common wire for the control of both relays, and the contact of relay WZ closes a circuit for the normal correspondence relay NWC when the relay WZ is energized with a polarity to operate the associated track switch to its normal position, and the circuit for the relay RWC is closed by the contact 65 in its left-hand position to correspond to the energization of relay WZ with a polarity to operate the associated track switch to its reverse position.

If the correspondence relays NWC and RWC, controlled as shown in Fig. 2, are substituted for the relays 4NCR and 4RCR respectively of Fig. 2 of the above mentioned Langdon patent, the switch repeater relay 4WP is no longer required for the control of the correspondence relays.

Having thus described a specific embodiment of a switch and signal control system, it is desired to be understood that the present invention is not limited to the specific form shown, and that various adaptations, alterations and modifications may be applied to the specific form shown to meet the requirements of practice without in any manner departing from the spirit or scope of the present invention except as limited by the appending claims.

What I claim is:

1. In combination, means for designating the respective normal and reverse positions to which a track switch is to be power operated, a point detector contact mechanism directly connected to the track switch, electro-responsive means solectively energized to normal or reverse positions to correspond with designated positions for the power operation of said track switch, normal and reverse switch correspondence relays having magnetic structures rendering them responsive only to a particular polarity of energization, and circuits for energizing the windings of said normal and said reverse correspondence relays respectively, said circuits being efiective to pick up said normal or said reverse correspondence relay only when said track switch and said electro-responsive means are in corresponding normal or reverse positions, said circuits including a pair of control wires extending from said point detector contact mechanism, said pair of control wires being common to circuits for the windings of both correspondence relays, and said pair of control wires being selectively energized with one polarity or the other by the operation of said contact mechanism, said correspondence relays being poled in their respective circuits to be responsive only to opposite polarities of energization of said pair of control wires, and each of said switch correspondence relays being disconnected at both sides of its windings from said pair of wires when the opposite position of the track switch is selected by said electro-responsive means.

2. The combination with means including normal and reverse switch control relays for designating normal and reverse positions for a track switch which has directly connected thereto a switch detector contact mechanism having contacts closed at respective normal, reverse, and intermediate positions of said track switch, of normal and reverse switch correspondence relays of a structure to be responsive only to a particular polarity of energization, and a circuit for the energization of the windings of each of said relays comprising a pair of control wires extending from the switch detector contact mechanism and common to the circuits for both relays energized with one polarity by said detector mechanism With said switch in its normal position, energized with the opposite polarity by said switch detector mechanism with said switch in its reverse position, and shunted by said detector mechanism with said track switch in an intermediate position, said correspondence relays being so poled in their respective circuits that said normal relay is responsive only to said one polarity of energization of said control wires, and said reverse relay is responsive only to said opposite polarity of energization of said control wires, and said circuit for each of said correspondence relays including a front contact for the corresponding switch control relay for said track switch in the circuit at one side of the relay winding and a back contact of the switch control relay for the opposite position in the circuit at the other side of the relay winding, whereby each of the correspondence relays has both terminals of its windings disconnected from said control wires when the opposite position of the track switch has been designated.

3. In a switch and signal control system having a power track switch, respective normal and reverse switch control relays for governing the operation of said power switch in accordance with selected normal and reverse positions that may be designated, a switch point actuated contact mechanism connected to said power track switch having pole changing contacts, respective normal and reverse switch correspondence relays for said power track switch, each of said switch correspondence relays being of a structure to respond to only one polarity of energization, a two-wire polarized circuit for the energization of said correspondence relays, circuit means including said two-wire circuit for energizing the winding of said normal correspondence relay directly by energy applied through said pole changing contacts of said contact mechanism, said circuit means including a front contact of said normal switch control relay at one side of the winding of said normal correspondence relay, and said circuit means including a back contact of said reverse correspondence relay at the other side of the winding of the normal correspondence relay, and'said circuit means being effective to energize the winding of said reverse correspondence relay directly by energy applied through said contacts of said contact mechanism and through said two-wire circuit, said circuit means for enengizing said reverse correspondence relay including a front contact of said reverse switch control relay at one side of the reverse correspondence relay winding and including a back contact of said normal switch control relay at the other side of the reverse correspondence relay winding, and said correspondence relays being oppositely poled with respect to energization of said two-wire circuit, whereby each correspondence relay can be actuated in response to energization of said two-wire circuit, only provided that the polarity of energization of the circuit extending to the contact mechanism is in correspondence with the energization of a particular one of said switch control relays.

WALTRUS L. LIVINGSTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,018,818 Thompson Oct. 29, 1935 2,027,569 Wight Jan. 14, 1936 2,049,923 OHagan Aug. 4, 1936 2,111,197 Thompson Mar. 15, 1938 2,299,275 Jerome Oct. 20, 1942 2,349,680 Shields May 23, 1944 2,378,751 Crago June 19, 1945 

